Simplex data communication systems, also known as one-way or passive systems, are employed in connection with paging. Generally speaking, one or more transmitters broadcast data communications. The communications include data which identify specific pagers. A population of pagers continually receive the broadcast communications. When one of the population of pagers identifies a communication directed to it, it alerts a subscriber to the incoming communication and often displays a numeric or alpha-numeric message carried by the communication. Due to the simplex nature of such systems, the system does not know when a pager fails to receive a communication directed to it. On the other hand, these simplex systems have many desirable features. Due to the absence of a transmitter and signal transmission capabilities in the pager, a small, low-power, light-weight, readily portable, and inexpensive unit results.
Conventional paging systems, such as terrestrial based systems, are capable of providing coverage only near commercially viable areas. This concentrated and local coverage restricts reliable delivery of messages outside of these areas.
Satellite communication systems provide a reliable propagation path for non-metropolitan users of paging services. Satellites receive transmitted information and convey it back to pagers on Earth. Transmission of paging information from geosynchronous orbit requires substantial power and a broadbeam transmission which inherently has limited capacity as spectrum is not generally partitioned and reused.
Lower Earth orbiting constellations may partition and reuse communication spectrum as is done with terrestrial cellular duplex communications. Channelized or cellular satellite communication systems may project a plurality of beams upon the Earth. Since propagation boundaries and partitions are not conspicuous, an orbiting satellite may expose a pager to the propagation of multiple cells or beams.
For reliable reception of transmitted messages, a pager would be required to monitor multiple beams from a satellite in order to provide a reasonable assurance that any paged data transmitted to a pager was properly received. Each needless monitoring of an empty paging beam consumes power available to a pager and shortens the life-expectancy of a pager's batteries.
Therefore, there is a substantial need for an improved messaging unit capable of extending the operational life of a pager power source.
There is also a substantial need for encoding and presenting information to a pager for use in evaluating which beams to monitor for an increased probability of paging data.